The present invention relates to an electronic disk subsystem for use with a data processing apparatus and, more particularly, to an electronic disk subsystem capable of reliably confirming the writing of data into an electronic disk unit thereof.
It has been customary with an electronic disk subsystem for the above application to cause an electronic disk unit thereof to confirm data written during a write mode operation by a read-after-write procedure. The problem with such a subsystem is as follows. Assume that an error has occurred in a counter built in the disk unit, e.g., the counter is not incremented due to an error although the start address for data transfer has been successfully loaded therein. Then, data would be written to the same address at all times, and the read-after-write operation would be effected at the same address, preventing the subsystem from detecting the error.